1. Field of the Invention
The subject invention relates to the ignition timing lights for internal combustion engines, and more particularly to adaptors for connecting such lights to engines utilizing spark plugs of various configurations.
2. Description of the Prior Art
In tuning up internal combustion engines and in testing their spark plugs and related ignition systems, the mechanic must have access to the central electrode terminals of the sparks plugs or the terminals of the spark plug ignition wires.
The design of modern engines and the increasing tendency to add more and more accessories to them generally make it extremely difficult to reach the spark plugs. Additionally, the central electrode terminal of each plug is usually covered by a resilient insulating protective sleeve which fits over the ceramic insulator plug and the end of the ignition wire attached to it. Frequently these sleeves become so deteriorated that they cannot be rolled back on themselves to expose the electrode terminals without being permanently damaged.
To overcome these problems, some mechanics resort to the practice of using a sharp instrument to pierce or cut the sleeve or the spark plug wire covering in order to make contact with the ignition circuit. Obviously, these methods are undesirable.
Prior art devices have been proposed which are intended to furnish access to the ignition circuit without need to damage the insulating component. A typical example of such devices is the Tune-Up Extention for Use With Spark Plugs for Testing Purposes described in McCord U.S. Pat. No. 2,853,691. Most of these devices, however, position the exposed contact surface close to the spark plug where, as with McCord's extention, it is just as inaccessible as the plug electrode terminal itself.
It is a primary object of the subject invention to furnish an electrical connector which can be quickly and easily connected in series between the terminal end of any of the spark plug wires and the associated plug's electrode terminal, and which contains a readily accessible attachment point for testing equipment such as a timing light, an oscilloscope, or one of the new-generation computerized engine analyzers.
For maximum utility, a connector of this type must be usable with all forms of internal combustion engines; but the spark plugs in such engines are not identically constructed. The electrode terminals on most automobile engine plugs are relatively large and are provided with annular detents adapted to cooperate with axially slotted resilient female slip-on terminal caps on the ends of the ignition wire leads originating at the distributor. Many sport cars and most smaller motorcycles use plugs having threaded terminals onto which the distributor or coil wire terminals are pressed.
Prior art electrical connectors have been designed for quick-mounting to spark plugs. The Electrical Connector shown in Bell U.S. Pat. No. 2,024,814 is typical of these. However, most such connectors are not usable with both types of plugs.
It is another object of the subject invention, therefor, to provide an adaptor for timing lights and similar test equipment which can be employed with plugs of both configurations.